Microsoft inbox DSM may not perform well on system with many processors

Performance may be less than expected when using the Microsoft DSM (Device Specific Module) with MPIO (Multipath I\O). For example, scalability issues may be seen on systems with greater than 32 processors.

The Microsoft DSM is intended to be a generic DSM that provides compatibility with a broad range of array hardware. Vendor DSM's may be able to take advantage of hardware-specific responses from the storage array and have the capability for greater performance. For example, a vendor-supplied DSM could take advantage of specific status codes to recover from I\O path failures more quickly than the generic Microsoft DSM. To reiterate:

• The Microsoft DSM should be used to obtain a basic level of functionality across a wide variety of arrays.  It is not intended for use in high performance scenarios.
• For scenarios where additional functionality or increased performance are desired, a vendor-provided DSM should be used.

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